I dont think he would ever side with Laheit, even if he promised Eternal Peace (unless of course, it is to decieve him), it would be near impossible for him to get that on the other side. Not only that he'd be hunted by the side of good but whose to say the other side wont betray him. His comprehension would alarm at all times, if he did. And thats not a peaceful life aint it?
At the very least, his comrades are good natured albeit a bit naive. Plus they know that he is literally no threat especially in straight up battle and knows that he only likes peace. the only way for him to turncoat is literally for them to make the first move. He doesnt decieve people for fun. All he does is to protect himself.. He is a self proclaimed coward after all.